Could a broken chassis-to-hood ground strap cause my battery to drain and various CEL codes?

[dukbludvl]

Hi All - appreciate your thoughts on this. 2003 GMC Yukon 5.3L 2wd with 175k miles. I've been driving these 00-06 Yukons for 22 years. Had a 2000 that I put 400k miles on, and a 2005 that I put 300k on, and I love these 00-06 model years so I bought this '03 used a year ago from the original owner after the trans went on my 05 (the 05 also had lingering engine issues, like low oil pressure, so I gave up on it but still have it sitting in the parking lot at the office).

QUESTION: My question is this -- could a broken chassis-to-hood ground strap (the short, foot-long strap that goes from the firewall to the hood, GM part number 15179982) lead to a host of odd electrical problems and check engine lights (CEL) AND drain my battery? I started checking my ground straps and this is the second one I looked at and with the slightest tug it came apart at the hood connection. I replaced it with a new one and am wondering if this is likely to have solved many or most of my weird electrical issues (see more on that below), including a variety of CEL codes and draining of 2 batteries.

HISTORY: Here's the history of what I've experienced in the past year or so:

November 2020: CEL came on, code was P0420 Catalyst System Efficiency Below Threshold Bank 1. CEL went off on its own after a week.
December 2020: CEL on again; ran 2 bottles of CataClean, CEL went off: over the past year, CEL has come on and off for the P0420 probably a dozen or more times;
December 2020: Replaced old battery with new Optima RedTop
January 2021: CEL on and "Reduced Engine Power" when warm starting; cycled on/off a few times and REP and CEL both cleared. Read stored codes as P0120 Throttle/Pedal Position Sensor A Circuit and P2135 Throttle/Pedal Position Sensor/Switch A/B Voltage Correlation.
January-September: Occasionally noticed on first start in the morning that I'd turn the key and the starter would seem to catch and crank 4-5 times before turning over (I could let go of the key and it would continue cranking until it started).
October 10, 2021: Optima Red Top (only 10 months old) totally dead. Replaced with new Napa Legend Premium wet battery.
October 20, 2021: New Napa battery was totally dead after sitting overnight. Jumped and worked fine for a week, then died again. Jumped and worked fine for a day or two, but then would be dead every monring.
November 4, 2021: Replaced alternator with new ACDelco reman 145amp.
November 9, 2021: CEL on again. Codes read as P0420-confirmed Catalyst Bank 1 again, P1516-confirmed Throttle Actuator Control Module, P0420-pending, P1516-history, C0298-history Powertrain Control Module (PCM) Indicates Traction Control Malfunction, C0267-history ABS Pump Motor Circuit Open
Early December 2021: On 2-3 cold and warm starts, got "Reduced Engine Power" indicator again. Was able to clear it by cycling engine on/off a few times.

After the new Napa battery I installed in October would no longer hold enough charge to start the vehicle even after sitting on a NOCO overnight, on December 16, 2021 I just installed a second new Napa battery and replaced the chassis-to-hodd ground strap that I found was broken/disconnected. So far, after 3 days, the new battery has not drained and the Yukon fires right up on the first try like it should.

My question is -- have I solved my battery drain issue, and possibly also the cause of some or all of the CEL codes, with a $6 part that took me all of a minute to swap out?

 

[Joseph Garcia]

Corroded ground connections are common on these trucks, and when this occurs, it causes major issues on the truck's electrical systems. I cannot tell you for sure if your electrical troubles will be over with what you have done, but I will tell you that if you found 2 bad ground connections, chances are that you have additional corroded ground connections. I recommend that you check all ground connections in the engine well and along the frame under the truck, and clean and re-attach any ground connections that look even the least bit corroded.

 

[MassHoe04]

I would expect the chassis to hood ground strap to not be the primary cause of your issues. Could be, but not my first thought.

Bad grounds could cause the computers to see all kinds of weird things, bit I still kind of doubt the chassis/hood strap would be the culprit.

If the negative ground from the battery terminal to the engine block ground bolt is bad, then I could see how the battery might not charge properly from the alternator and drain every time you started. The engine would run off the alternator while the engine was running, but the battery would take a hard hit every time the starter kicked over. Eventually, the battery would die, if not getting a charge off of the alternator. I would start with looking at the negative cable from the battery post to the ground point. Of course, all the other grounds are important and should be inspected and cleaned if needed.

If the issue is not a bad connection on the negative cable, you may have a short somewhere.

If cats are originals and over 100k miles, there is a very good chance the 420 codes are sensor related (if not the actual cat failing). I would think about some quality O2 sensors, if they are due for replacement.

Good luck!

 

[SSpinball]

no that would only effect components on your hood like under hood light.

 

[rockola1971]

Hood ground is there for corrosion preventative measure by keeping all metal parts at the same voltage potential which is ZERO on the chassis (AKA Ground). Sounds more like your old battery has had a cell going bad for awhile and finally gave up when it wouldnt start the vehicle after sitting overnight. The low voltage output taxed the alternator and loaded it down because the bad cell was loading the alternator down causing the PCM and other modules to see low B+ (AKA 12v+). Without a proper ground and 12v reference you can get all kinds of nuisance codes and engine control problems causing poor performance such as bad idle, poor mileage and high emmissions.